RosettaCodeData/Task/Anonymous-recursion/Yabasic/anonymous-recursion.basic

print Fibonacci(-10)
print Fibonacci(10)


sub Fibonacci(number)

    If number < 0 print "Invalid argument: "; : return number

    If number < 2 Then
        Return number
    Else
        Return Fibonacci(number - 1) + Fibonacci(number - 2)
    EndIf

end sub